Defence says risks in all sub bidders

Japan hasn't exported any defence equipment in the last 50 years but Defence says that's a risk that would have to be managed if the Japanese Soryu is chosen as Australia's new submarine.

Defence department secretary Dennis Richardson said that absence of exporting experience was certainly one of the risks of dealing with Japan.

He said there were other risks in dealing with the other two contenders for the submarines deal, German firm TKMS and French firm DCNS. Both are proposing new designs for vessels that don't yet exist.

"We are conscious of what we might need to manage in that context. Each of the potential design partners carry different kinds of risks which will need to be managed," he told a Senate estimates committee said

Shadow defence minister Stephen Conroy pointed to an article by a Japanese defence official who said Japan's long absence from the global defence market meant the country would be better off focusing on exporting disaster relief and reconnaissance capabilities.

Mr Richardson said this wouldn't be the first time a government had taken a different view to an official.

"Clearly the Japanese government has taken a decision that it will compete in this process and take on the challenges that are involved," he said.